The prior art includes various lost motion devices for adjustably controlling valve lift during cam rotation in an internal combustion engine. At low engine speeds, it is desirable to reduce cam lift to minimize the amount of air drawn into the cylinder to optimize efficiency and improve torque.
Prior art cam driven hydraulic lost motion devices achieve lost motion by bleeding fluid from a high pressure chamber. These systems do not optimize efficiency even with a recovery system, such as a spring-loaded accumulator, because fluid is pumped across a small orifice, which results in throttling losses.